Fumigant and process of fumigation



Patented Dec. 30,1924. i i 5 i UNITED STAT-ESPATENT OFFICE.

HARRY HOUGHTON, F GLEN ECHO, MARYLAND.

FUMIGANT AND'Z PROGESS OF FUMIGATION.

No Drawing. Application filed June 21, 1924; Serial No. 721,565.

To all whom it may concern: Experiments have also been made looking Be it known that I, HARRY W. Houcnrox, toward the use as a fumigant of a mixture a citizen of the United States, residing at of hydrocyanic acid gas and formaldehyde. Glen Echo, county of Montgomery, State of While the formaldehyde possesses a certain Maryland, have invented an Improvement warning quality it has been found in pracin F'umigants and Processes of Fumi ation, tice that the mixture of the hydrocyanic acid for which I made application for tters gas and the formaldehyde does not act as a Patent of the United States on December 5, single gas, the mixture not continuing until 1922, and have invented certain improve both aredissipated, but on the contrary; it 10 ments therein, of which the following de-e has been found that the hydrocyanic acid scription is a specification. gas and formadehyde separate and stratify, This invention relates to an improved and thatthe formaldehyde is more rapidly fumigant and process of fumigation. dissipated than the hydrocyanic acid gas so Heretofore, the principal fumigants used that the latter is liable to persist in lethal 15 have been hydrocyanic acid, carbon monoxconcentrations after the formaldehyde has ide and sulphur dioxide. All of these posbeen dissipated, and persons entering places sess the necessary lethal quality, sulphur fumigated with this mixture are liable to dioxide/in a lesser degree than the other two, be overcome, the fumigant having lost its but their use is open to serious objections. warning quality. The odor of hydrocyanic acid is relatively The fumigant in accordance with the presslight and carbon monoxide is odorless and cut invention is free from the above objec- 'neither of these gases possesses any other tions. It consists of a gas combining the warning characteristic. They are therefore necessary lethal quality with a warning extremely dangerous to human beings and quality so manifest and unmistakable that 25 many casualties have occurred in their use the presence of the fumigant, even in nonas fumigants. Furthermore, hydrocyanic lethal concentrations, must be immediately acid is not very readily difi'usible, is liable detected by any human being andwill to collect and remain in poorly ventilated in fact make it impossible for the human spaces, and in cold spaces is liable to-conbeing toremain in the presence of the fumi-- so dense and then be volatilized when such gant because its lachrymatoryeffect is un- I 45 sary to prolong the period of fumigation, more so than the hy spaces become heated hours or even days bearable. For the formation of such a gasl 5 later, so that persons entering such spaces preferablyv use a mixture of hydrocyanic a considerable periodafter fumigation had acid and a cyanogen haloid, preferably cybeen effected have been overcome without anogen chloride. While the proportions as warning. Carbon monoxide requires such. may vary considerably according tothe specomplicated apparatus for its generation cial conditions under which the fumigant is that its use is greatly, restricted and this to be used I generally use a mixture containgas furthermore is valuelessfor the d'estruc- ,ing approximately 25% of hydrocyanic acid tion of the lower forms of animal life, such and 75% of cyanogen chloride. In this mix- 40 as fleas, flies, mosquitoes, etc., even after ture the cyanogen chloride is the warnin long exposure and in a highly concentrated gasowing to its lachrymatory property, an state. 7 the use of this gas as thew'arnmg agentThas Sulphur dioxide is of relatively low toxic the added advantage that this gas is also quality and difi'usibility so that it is necesl thal nd qually :ifiective (and perhaps rocyanic acid in some which makes its use undesirable and often a e articularly bacteria and eggs of aniimpracticable. Even then, owing toits low mals and insects) in the .exterminationof difl'usibility and lack of penetration, aniim l d i t t such as rats, bats, mals concealed in pockets or spaces between .bedbugs, roaches, mosquitoes, flies, fleas and packages are liable to escape the effect of lice, and bacteria, including disease germs. I this gas. In the presence of dampness sul- The lachrymato effect of the above menphur dioxide also forms an acid which in tioned mixture of ydrocyanic acid and cg" jures tissues, articles of clothing, foodstuffs, anogen chloride, due to the presence of t e seeds, etc. J latter, is so severe, even in non-lethal concentration, that human beings cannot remain ing but, remaining asa substantially perfect mixture. "It is also fo und that the gaseous mixture constituting this invention is dissipated very. rapidly by ventilation, and the cyanogen chloride gas is not disvsipated more'rapidly thanthe hydrocyamc acid gas ed that the fumiga'nt retains its warning uality until all the hydrocyanic acid gas as been dissipated, and persons entering spaces which havebeen 'fumigated with this fumigant will receive full warn ing untilafter all danger is passed. This fumigant is also non-corrosive to metals, and1 non-injurious tofabrics and other substances, includin' plant life; .it is easlly manufactured, .0 low cost and free-from dangeriof explosion and fire if proper proportions of the ingredients are used. Besides bein destructive. to animal life, this fumigant is an efficient germicide, insecticide-fund disinfectant.

- In practicing the invention it is preferable to generate t e gas mixture at the place where it is .to be used, that is to say, within the spacees to be fumigated, or near the plants, trees or other objects that are to be reached. .A mineral acid, preferably concentrated hydrochloric acid diluted with an equal volume of water, is placed in an open vessel and to thisacid there is added a mixture of a water soluble cyanide and a water soluble oxidizin agent, preferably a chlorate. It is pre erred to. use dilute ,hydrochloric-acid instead of the concentrated bydrochloric acid so as to avoid theformation of objectionable "oxides of chlorine which are 'hlghly inflammatory or; explosive;' It] is also preferred to use the cyanides-and' chlorates of the alkali metals, owing to their cheapness and "ready" availability. ,They may be dissolvedin 'water' or used-dry. If used dry,- .preferably they aresup'pli in'the form ofcoarse granules, sons to, avoid hazards of fire andexplosiion to whichiinix tures of the finelyg powdered materialsare' sub ect. These {hazards mayj be largely overcome by coating the chlora some inert substance or -'material example a silicate, such-as powde aka;

the proportion of talc may be approximate-'- ly 25% in weight of the entire-mixture. Th1s coating of the chloratefwith an inert Substance or material maybeQpjpl-ied to acid, the said coarse granules as well as tothe powdered,

chlorate and will remote safety in storing, transportation and handling of mixtures of cyanide and chlorate.

.The cyanogen chloride and. hydrocyanic' acid gas are generated, preferabl by a continuous reaction involving theli ration q of nascent chlorine in, an aqueous solution of' a cyanide salt. acidified with hydrochloric chlorine in this specific case being liberated from an oxidizin reagent like a chlorate of an' alkali meta preferably sodium or potassium chlorate. The ingredients may,-as already stated, be used in different proportions according to cir cumstances, The following proportions have been found in practice to be very satisfactory: For -every 1000 cubic feet of space use' from one to five ounces of sodium or potassium cyanide; from one to four ounces of potassium chlorate; and from 100 to 600 cubic centimeters (3 to 20 fluid ounces) of concentrated -commercial hydrochloric. acid diluted with .an

equal quantity of water. In other, cases I have used about four ounces of sodiuni or potassium cyanideto about two ounces of sodium or otassium .chlorate. and 17 fluid ounces 0 hydrochloric acid diluted with an equal amount of water, but as already stated the proportions may vary.

The reaction may be expressed by the following equations, depending upon the" proportions of the ingredients used, as indicated by the subtended atomic weights;

The amounts of hydrocyanic acid gas and concentrated commercial free chlorine "evolved will depend somewhat,

upon the nature of the ingredients, the surrounding temperature, and other conditions subject to fluctuation, as well as' upon the proportions of the ingredients used.

The sodium or potassium cyanide and sodium or potassium chlorate. may be dissolved in water equal in volume to the concentrated hydrochloric acid, or they may be mixed in a cloth bag which may then be dropped into the dilute hydrochloric acid. Generation of the fumigant then takes place, starting slowly and with cyanogen chloride predominating. The fumlgant thus generated contains about 25% 'of hydrocyanic acid gas and about 75% of'cyanogen chlo ride gas, in addition to some free chlorine.

In conducting the fumigation the ingredients should be ready and at the place of operation. The operator. may use a gas mask, but this is not absolutely necessary.

owing to the warning characteristic of the fumlgant, even in non-lethalconcentrations. Usually about an hours exposure of the space to 'be fumigated to the fl tion of the i i This fumigant fumigant will sufiice to produce the desired effect and at the end of this period the operator, wearing a mask, opens the windows, doors or covers, whereupon dissipation of the fumigant occurs very rapidly, the hydrocyanic aci gasand cyanogen chloride gas dissipating together, the cyanogen chloride gas remaining so thus persisting so drocyanic? acid gas present, so that when the lachrymatory effect has disappeared one may be sure that all hydrocyanic acid hasalso disappeared and that all danger to human life has passed. i

is also valuable as a starilizer and germicid e. As a sterilizer, germivegetation in general the lfumigant may be dissolved in water which is then used as a spray. The fumigant is readily soluble in water which absorbs anywhere from one to parts of the fumigant ,to one part of readily be regulated water. Bugs, insects, germs or bacteria will be destroyed by this spray which retains its effectiveness for three or four hours, and in proper concentration is 'not injurious to plant life. The strength of according life to be treated. Here matory effect of the vfumigant persists until to the plant all hydrocyanic acid gas has beendissi- .pated so that alldanger avoided.

m human life is Another advantage of this fumigant is that it is notv retained by foods,-tests made with foods which had been fully exposed to the action of the fumigant in-spaces' during fumigation showing that these foods were absolutely free from the fuinigant. Milk,

for example, the absorbentv .ualitiesof which for gases is well known, an which had been I fully exposed to the action of the fumigant .fect whatever upon these.

in spaces to rats and mice without any apparent ef- Milk thus exposed was also consumed human beings with impunity, there being neither taste nor odor of the fumigant left therein. The foregoing description is believed to be sufliciently comprehensive to enable the manner of practicingv the invention for'the various purposes illustrated to be fully understood, butthe invention is obviously.ap:,- silicate compound. plicable to all kinds of fumigation, includ-'- bacteria.

' cific gravity than air, which What I claim as my invention and desire to secure by Letters. Patent is: v

1. A fumlgant. containing hydrocyanic acid gas and a warnin lachrymatory cyanogen derivative gas aving greater 'spe-' combine to form long as there remains any hydrocyanic acidgas, the lachrymatory efiect I acid gas and cyanogen long as there is any hytion of cyanogen the spray canagain the lachryfumigated, was tested by being fed a permanent gas mixture heavier than-air 1 diffusing and dissipating without separa- 3. A fumiga'nt containing hydrocyanicchloridein predominant lachrymatory proportions.

4. A fumigant containing hydrocyanic acid gas and a cyano-gen haloid in propor- A A tions to form a substantially permanent gas freelysoluble in water.

5. A fumigant containing hydrocyanic acid gas and cyanogen chloride generated simultaneously. 6. A fumigant produced by the simultaneous generation of cyanogen haloides and hydrocyanic acid gas.

7. A fumiga-nt resulting from the evolved gaseous reaction of a cyanide, and hydrochloric acid. I

8. A fumigant produced by the generachloride and hydrocyanic acid gas by liberating nascent chlorine in an aqueous solution of a cyanide acidified by hydrochloric acid.

9. A fumigant produced by the H 'generation of cyanogen chloride and hydrocya'nic acid gas by liberating nascent chlorine in an aqueous solution of a cyanide and an oxidizing agent acidified by hydrochloric aci t 10. A fumigant produced by enerating cyanogen chloride and hydrocyapic acid gas by liberating nascent chlorine in an aqueous solutionof a cyanide acidified with hydrochloric acid by the additionoi a'chlorate compound. v r

11. A fumigant produced by. generating cyanogen chloride and hydrocyamc acid gas by liberating nascent chlorine in anaqueous solution of a cyanide acidified with hydrochloric acid by the addition of a chlorate compound protectively coated'with stance inert to'the action of the acid.

12. A fumigant produced by generatin gas by liberating nascent chlorine in an cyanogen chloride with hydrocyanic aci Q a chlorate a sub-v aqueous solution of a cyanide acidified with hydrochloric acid by the addition of a chlo- 13. A fumigant producedby generating cyanogen chloride and hydrocyanic acid-gas rate compound protectively coated witha w by liberating nascent chlorine irf'an aqueous solution of a cyanide acidified with hydrochloric acid by the addition ofa' chlorate compound protectively coated with talc.

14. A fumigant produced by generating cyanogen chloride by liberating nascent chlorine solution of a cyanide acidified with h chloric acid by the addition ofa c droand'h-ydrocyanic acid gas in an aqueous orate .amo'nnt of hydrochloric acid and water in equal ,proportions.

. 16. A fumigant comprising a plurality of gases, one of which is hydrocyanic acid gas and one of Which is cyanogen halpid in proportions to form a gaseous combine having a greater specific gravity than air.

17. A fumigant comprising a warning lachrymatory and lethal cyanogen derivative gaseous combine heavier than air, soljuble in water and diffusing and dissipating freely without separation.

18. A mixture of a cyanide and an oxidizing agent, the latterbeing coated with v 19. A mixture of sodium cyanide and a chlorate in which the particles of the latter are coated with talc or some other inert substance for the purpose described.

20. A mixture containing sodium cyanide and sodium chlorate in which the particles ofsodium chlorate are coated withtalc or some other inert substance, the proportions being such as to cause liberation of hydrooy- 'anic acid gas and cyanogen chloride when acted upon by hydrochloric acid.

In testimony whereof, I have signed my name to this specification.

HARRY W.- HOUGHTON. 

